The invention relates to an apparatus for the metered removal of pasty or fluid substances from a storage container having an outlet nozzle which is disposed at the upper container end and can be introduced into a self-closing bottom valve of a mixing container, and having a plunger which can be actuated by a piston rod to exert a feed pressure on the interior of the storage container.
Apparatus of this type are used for example for cosmetic preparations, in particular hair dyes and for mixing their components. In this connection there are many storage containers available from which the substances to be mixed are to be removed and introduced successively into a mixing container. Some of the substances have a strong colouring effect or react chemically with one another or with the atmospheric oxygen, should be removed so that there are as few losses as possible and should be introduced directly into the mixing container so as to avoid contamination.
In the case of a known apparatus of the initially mentioned type (German specification No. 28 27 610) a piston feed pump is arranged in the storage container and has its piston cylinder screwed to the storage container. A hollow piston rod, connected to the plunger, projects out of the piston cylinder and bears the outlet nozzle at its upper end. The mixing container is placed with its self-closing bottom valve on this nozzle; a pressure is exerted on the piston rod and thus on the plunger in order to convey the substance to be removed, which may be pasty or fluid, upwards into the mixing container.
The structural expenditure required in this connection for each individual storage container is comparatively great since each storage container has to have its own pump which in each case contains two non-return valves and a spring. These parts are in constant contact with the substance to be conveyed. At the end of the removal process a relatively large amount of the substance remains in the piston cylinder and on the piston rod; these lost amounts can no longer be conveyed.